New research has highlighted the potential risk of tens of thousands of inactive offshore oil and gas wells remaining unplugged in the U.S., which could lead to leaks into the ocean. The study, published in Nature Energy, revealed that over 14,000 inactive oil and gas wells in the Gulf of Mexico’s offshore waters, inland waters, and wetlands have not been plugged and abandoned. Plugging these wells could help mitigate environmental risks, but researchers estimate the cost to exceed $30 billion.
Approximately 82,000 wells have been drilled in the coastal waters of Louisiana, Texas, and Alabama. Researchers combined federal and state agency data on offshore wells in the Gulf of Mexico and discovered that the number of non-producing, unplugged wells is higher than the number of active wells in the region. Gregory Upton, Interim Executive Director of Louisiana State University’s Center for Energy Studies, noted that oil and gas operations for offshore and coastal waters are significantly more expensive than onshore operations.
Around 13,000 active wells are located in state or shallow federal waters, heightening environmental risks. Methane released from deepwater wellheads is less likely to reach the surface, but shallow wells closer to the surface are more likely to impact the coastal ecosystem, said Mark Agerton, Assistant Professor at the Department of Agricultural and Resource Economics at the University of California, Davis. Methane leaks from shallow water infrastructure are also more likely to reach the surface.
Offshore and coastal water wells, which account for less than 3% of all wells ever drilled in the U.S., have contributed to approximately 15% of all U.S. oil production over the past two decades. Federal and state rules require operators to plug and abandon wells when oil or gas production ceases. However, in some states, it is relatively easy to obtain extensions for plugging these wells.
Orphan well programs exist in some states, where the state takes legal responsibility for site restoration when no financially viable company can be held liable for plugging the wells. However, very few of these wells have been plugged using funds from orphan well programs, given the higher costs of oil and gas operations in offshore and coastal waters compared to onshore.
The study emphasizes the environmental importance of prioritizing the plugging of state and shallow water wells and highlights the potential financial liability for companies.
